Dentinal hypersensitivity is acute, localized tooth pain in response to physical stimulation of the dentine surface by thermal (hot or cold), osmotic, tactile, and/or a combination of thermal, osmotic, and tactile stimulation of the exposed dentin. Exposure of the dentine, which is generally due to recession of the gums, or loss of enamel, frequently leads to hypersensitivity. Dentinal tubules open to the surface have a high correlation with dentinal hypersensitivity. Dentinal tubules lead from the pulp to the cementum. When the surface cementum of the tooth root is eroded, the dentinal tubules become exposed to the external environment. The exposed dentinal tubules provide a pathway for transmission of fluid flow to the pulpal nerves, the transmission induced by changes in temperature, pressure, and ionic gradients.
To relieve dentinal hypersensitivity, dentinal tubules may be plugged. Such occlusion may be carried out either by blocking the tubule with a particle of smaller size than the tubule or by inducing precipitation within the dentin tubule itself.
Tin (II) fluoride (also known as stannous fluoride, SnF2) has been used in oral care compositions, but has disadvantages. Tin (II) may react with other ingredients of the oral care composition to form insoluble inactive tin compounds, thereby reducing the effective amount of available tin (II) in the composition. In addition, tin (II) fluoride may cause yellow-brown tooth staining and may impart unacceptable astringency to the composition.
While the prior art discloses the use of various oral compositions for the treatment of dentinal hypersensitivity, there is still a need for additional compositions and methods that provide improved performance in such treatments.